House Dust Mites Confer a Distinct Immunological Feature among Dermatitis

Atopic dermatitis (AD) is a heterogeneous disease with regard to clinical phenotype and natural history. We investigated T cell subtypes and cytokine responses in peripheral blood and skin lesions of AD patients with various sensitivities. Immunological studies were performed in 27 subjects: 9 house dust mite (HDM)-sensitized; 6 subjects with sensitizations other than HDM; 7 non-allergic AD patients and 5 healthy controls. Among those, skin biopsy samples of 13 subjects were evaluated for immunohistochemical analyses, as well. The mean age was 8.93±5.17 years. HDM-allergic AD emerged as a distinct immunologic phenotype, with higher production of interleukin (IL)-4, -5, -2 both at rest and when stimulated by Der p1 or SEB along with higher Th17. As for T H 17 cell percentage, it was increased in all AD groups compared to healthy controls, while HDM-allergic group was distinguished with a significantly lower production of IL-17. Patients with sensitizations other than HDM were mostly similar to non-allergic AD, with increased Th17 and CD4 + CD69 + interferon-gamma (IFN-γ) + T cells percentage. The biopsy of lesional skin showed that HDM-allergic AD had lower IFN-γ and IFN-γ co-expressing CD8 + T cells compared to patients with other sensitizations ( p =0.03 and p =0.04, respectively). Among the HDM allergic patients, pairwise comparison of lesional versus non-lesional skin revealed higher CD4 + T cells numbers, expression of forkhead box P3 (Foxp3) and T-cell-specific transcription factor (T-bet) ( p =0.018, p =0.018, p =0.018, respectively). HDM-allergic AD is a distinct subtype with a predominant skewing in Th2 and higher Th17 cell percentage along with a blunted Th1 response in the skin, all of which may have therapeutic implications.